The present invention relates to electrostatic precipitators for removing suspended particles from a flowing gas, and more particularly to a collecting electrode structure for use in electrostatic precipitators.
Electrostatic precipitators are used for electrically separating particles suspended in a gas flow. They include charging electrodes which charge the particles suspended in the gas flow, and collector electrodes which collect the charged particles. In one known type of electrostatic precipitator involving a horizontal flow of the particle-laden gas, the collector electrodes include substantially planar bases fixed vertically substantially parallel to the gas flow and include a plurality of spaced projections projecting laterally into the gas flow. The purpose of the projections is to serve as barriers to create stagnant zones or reduced-velocity zones. Such stagnant or reduced-velocity zones decrease the re-entrainment of the collected particles back into the gas flow.
One known example of collector electrode of this type is described in U.S. Pat. No. 3,807,140, wherein the projections are perforated with apertures for the passage of the gas therethrough. The free ends of the flat projections terminate in tubular edgings in order to reduce distortions of the electric field. A disadvantage of such a construction, however, is that, in order to considerably reduce the re-entrainment of the collected particles back into the gas flow, it is necessary to use tall perforated projections. These cause excessive distortion of the electric field which decreases the efficiency of the electrostatic precipitator particularly in removing particulate matter from stack gasses.
Another known construction, as described in Russian Patent No. 784076, includes perforated projections having free ends in the shape of oval gutters formed with convex surfaces facing the direction of the charging electrodes; i.e., opposite to the direction of the collector electrode base. Such gutters are intended to diminish distortions of the electric field. However, they create vortices and powerful turbulences which increase re-entrainment and decreases the residence time of the particles.